Lysis of HA-1⁺ or HA-2⁺leukemic cells by ex vivo–induced HA-1– and HA-2–specific CTLs. Data are representative for all ex vivo–induced CTLs. The lysis of same target cells by in vivo–induced HA-1– and HA-2–specific CTLs, and by control HLA-A*0201–specific CTL clone are shown for comparison. Target cells: HA-1⁻ or HA-2⁻ EBV-LCL (△); HA-1⁺ or HA-2⁺ EBV-LCL (▧); leukemic cells positive for HA-1 (n = 4) or HA-2 (n = 3) (⧫); HA-1⁺ or HA-2⁺ leukemic cells cultured with IFN-γ + TNF- (◍).